Functional regulation by ethylene throughout the cotton life cycle

Ethylene plays a crucial regulatory role at multiple stages throughout the life cycle of cotton. Accumulating evidence indicates that the regulatory function of ethylene in cotton is unique. First, ethylene exerts a dual regulatory effect on cotton, in which moderate amounts promote seedling growth and maturation, whereas excessive amounts induce undesirable effects such as leaf shedding, abnormal plant structure, premature senescence, and reduced yields. Second, ethylene is involved in crosstalk with other hormones, such as GA, ABA, JA, and BR, which collectively regulate processes such as seed development, vegetative growth, fiber development, and environmental stress responses. Additionally, ethylene plays a central regulatory role in the functions of chemical defoliants and harvest aids and is thus regarded as a key target for modulating the processes of shedding and maturation in mechanized cotton harvesting management. We systematically summarized the roles of ethylene in the developmental regulation, stress response, and harvest management of cotton and hope to provide an overview for the future development of targeted breeding and precision regulation strategies.